1. Field of the Invention
The present invention relates to a bearing holding structure and a motor having the same.
2. Description of Related Art
Conventionally, as shown in FIG. 4, a motor 11 has a cylindrical yoke housing 12 with a bottom, a plurality of magnets 13 fixed to an inner surface of the yoke housing 12, a rotor 14 disposed in a space of the yoke housing 12 on an inner side of the magnets 13 and an end frame 15 fitted to an opening 12a of the yoke housing 12.
The end frame 15 is provided in a center thereof with an axially outward protruding cylindrical portion 15a. The cylindrical portion 15a is provided in a center thereof with an axially outward further protruding bearing holding portion 15b having a bottom. A through hole 15c, into which a rotor shaft 14a of the rotor 14 is inserted, is formed in a bottom center of the bearing holding portion 15b. A disk shaped holding plate 16 is fitted to the cylindrical portion. The holding plate 16 is provided in a center thereof with an axially inward protruding cylindrical bearing holding portion 16a. 
A metal bearing 17, which holds rotatably the rotor shaft 14a, is held by the bearing holding portions 15 and 16. An outer circumfential surface 17a of the metal bearing 17 is formed in a spherical shape. Respective holding surfaces 15d and 16b of the bearing holding portions 15b and 16a are formed in combination thereof in a spherical shape corresponding to that of the outer circumfential surface 17a. The metal bearing 17 is sandwiched between and held by the end frame 15 and the holding plate 16 without moving axially and circumferentially in a state that the outer circumferential surface 17a is in an intimate contact with the holding surfaces 15d and 16b. 
However, it is difficult and expensive in manufacturing to form in the end frame 15 and the holding plate 16 the spherical holding surfaces 15d and 16b whose each curvature is equal to that of the outer circumferential surface 17a of the bearing 17.
Further, as the conventional motor has a structure that the holding plate 16 is fitted into the cylindrical portion 15a of the end frame 15, the holding plate 16 and the cylindrical portion 15a are required to be formed with high dimensional accuracy for an axial alignment of the same, resulting in higher manufacturing cost.